Effects of Subphase pH and Temperature on the Aggregation Behavior of Poly(lauryl acrylate)-<i>block</i>-poly(<i>N</i>-isopropylacrylamide) at the Air/Water Interface

You, Kun; Wen, Gangyao; Skandalis, Athanasios; Pispas, Stergios; Yang, Shicheng; Li, Hongfei; Sun, Zhaoyan

doi:10.1021/acs.jpcc.9b01320

Cited by 15 publications

(48 citation statements)

References 44 publications

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“…When the temperature is higher than the LCST of PNIPAM, the core–shell structures are destroyed and the drug is released . More recently, we found that amphiphilic diblock copolymer poly(lauryl acrylate)- block -poly( N -isopropylacrylamide) (PLA- b -PNIPAM) exhibited the LCST behavior at the air/water interface under neutral and alkaline subphase conditions, which is consistent with that of PNIPAM-containing copolymers in aqueous solutions. Furthermore, it has been found that salt ions, particularly anions, have significant effects on the LCST of PNIPAM aqueous solutions related to the famous Hofmeister series. − The typical order of the anion series is as follows: CO 3 2– > SO 4 2– > S 2 O 3 2– > H 2 PO 4 – > F – > Cl – > Br – ≈ NO 3 – > I – > ClO 4 – > SCN – .…”

Section: Introductionsupporting

confidence: 79%

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Anion Specificity Effects on the Interfacial Aggregation Behavior of Poly(lauryl acrylate)-block-poly(N-isopropylacrylamide)

et al. 2019

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Aggregation behavior of an amphiphilic diblock copolymer poly(lauryl acrylate)-block-poly(N-isopropylacrylamide) (PLA-b-PNIPAM) on neutral aqueous subphases with different salt species and salt concentrations, as well as the structures of its Langmuir−Blodgett (LB) films, were systematically studied. The presence of NaCl or Na 2 SO 4 in subphases makes PNIPAM chains shrink on the water surface and reduce their solubility underwater. On the contrary, the presence of NaNO 3 or NaSCN makes PNIPAM chains more stretched on water and increase their solubility underwater, whose stretch degree and solubility both increase with the increase of salt concentration. Solubility of PNIPAM chains in the above subphase solutions is ranked as NaSCN ≫ NaNO 3 > pure H 2 O > NaCl ≈ Na 2 SO 4 , which is almost consistent with the Hofmeister series except for the latter two close cases. All the initial LB films of PLA-b-PNIPAM exhibit tiny isolated circular micelles. Upon compression, the LB films in the case of pure H 2 O exhibit the dense mixed structures of circular micelles and wormlike aggregates. The formation of wormlike aggregates is due to connection of some adjoining cores, which is less possible in other subphase cases because of the conformation difference of PNIPAM chains.

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Section: Introductionsupporting

confidence: 79%

“…The weight-average molecular weights of PLA and PNIPAM blocks in the copolymer PLA- b -PNIPAM were 6000 and 12 000, respectively . HPLC-grade chloroform was used to prepare the spreading solution of PLA- b -PNIPAM (0.50 mg/mL).…”

Section: Methodsmentioning

confidence: 99%

Anion Specificity Effects on the Interfacial Aggregation Behavior of Poly(lauryl acrylate)-block-poly(N-isopropylacrylamide)

et al. 2019

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“…32 At low ionic strength (0.15 mol/L), the A 0 values of PDMAEMA18%-PLMA appear at large mmA (>15 nm 2 ). This is because the strongly hydrated anions (Cl − and SO 4 2− ) can polarize the water molecules 34 surrounding the short protonated PDMAEMA blocks and thus destroy their hydrogen bonds, resulting in the adsorption of the latter to the interface. Upon compression, an obvious plateau appears at 12 mN/m corresponding to the PDMAEMA submergence in water, which is similar to that appearing under alkaline conditions without salts.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…After a 20 min period for the full evaporation of THF, each initial surface pressure was below 0.20 mN/m. Finally, the monolayer was compressed by the symmetrical movement of two barriers (5 mm/min), and each isotherm was obtained with two almost overlapped curves . During the hysteresis measurement, the Langmuir monolayer was compressed to mm A of 5 nm 2 and maintained for 30 s, and then the barriers moved to the start positions.…”

Section: Methodsmentioning

confidence: 99%

Effects of Ionic Strength and Ion Specificity on the Interface Behavior of Poly(dimethylaminoethyl methacrylate)–Poly(lauryl methacrylate)

et al. 2021

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The ion specificity effect on the water solubility of poly(N-isopropylacrylamide)-containing copolymers complies with the Hofmeister series, which is applicable to other copolymers or not need to be explored. In this work, effects of ionic strength under acidic conditions and ion specificity under alkaline conditions on the air/water interface behavior of two amphiphilic diblock copolymers poly-(dimethylaminoethyl methacrylate)−poly(lauryl methacrylate) (PDMAEMA-PLMA) were systematically studied. Under acidic conditions, the surface pressure−area isotherms of a predominantly hydrophilic copolymer are insensitive to ionic strength. In contrast, the isotherms of a predominantly hydrophobic copolymer successively shift to the large, small, and large molecular area with the increase of ionic strength. Under alkaline conditions, the interfacial stretch degrees of PDMAEMA chains of two copolymers change with salt species and concentrations, which do not comply with the Hofmeister series. All of the Langmuir−Blodgett films of the former copolymer exhibit separate circular micelles. Nevertheless, those of the latter copolymer obtained under alkaline conditions exhibit various distinctive morphologies such as separate circular micelles, large separate PLMA cores within large PDMAEMA domains, and large PLMA domains/aggregates surrounded by short PDMAEMA shells. It can be attributed to the high deformability of PLMA chains, the ion specificity effect on the stretch degree of PDMAEMA blocks, and their underwater solubility upon compression.

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“…However, their isotherms at 40 C significantly move to the right with the A 0 values of 16.1 and 16.2 nm 2 , respectively. This is because high temperature increases the mobility of the cationic blocks 35 whose electrostatic repulsion makes them more stretched. At 40 C, the collapse pressure of qPDMAEMA87%-PLMA (40 mN/m) is higher than that of qPDMAEMA30%-PLMA (15 mN/m) because the stronger underwater electrostatic repulsion between the longer qPDMAEMA chains delays the monolayer collapse.…”

Section: Subphase Temperature Effect On the Isothermsmentioning

confidence: 99%

Aggregation behavior of the strong amphiphilic cationic diblock polyelectrolytes at the air/water interface

Ding

Wen

Chrysostomou

et al. 2021

J of Applied Polymer Sci

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Effects of subphase temperature and pH on the interfacial behavior of two strong amphiphilic cationic diblock polyelectrolytes, quaternized poly(2-[dimethylamino]ethyl methacrylate)-block-poly(lauryl methacrylate) (qPDMAEMA-b-PLMA), were studied by the Langmuir film balance techniquefor the first time. The morphologies of their Langmuir-Blodgett (LB) films were studied by atomic force microscopy. At the air/water interface, surface micelles with hydrophobic PLMA cores and hydrophilic qPDMAEMA coronas form. With the increase of temperature, the condensed surface pressuremolecular area isotherms move to large area (right shift). The higher the temperature, the more obvious the isotherm shifts to the right. At low temperature, the isotherms of the two copolymers are almost respectively overlapped under different subphase pH conditions. At high temperature, however, the isotherms of the two copolymers show some subphase pH dependence. All initial LB films obtained at different subphase conditions exhibit isolated circular micelles. Under different subphase pH conditions, the diameters of the micelle cores in the two copolymers' LB films obtained at low temperature are close but larger than those at high temperature, which phenomenon is first reported. This is probably due to the relatively lower mobility of polymer individual chains at low temperature, resulting in their higher local surface concentration and larger aggregation.

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Effects of Subphase pH and Temperature on the Aggregation Behavior of Poly(lauryl acrylate)-block-poly(N-isopropylacrylamide) at the Air/Water Interface

Cited by 15 publications

References 44 publications

Anion Specificity Effects on the Interfacial Aggregation Behavior of Poly(lauryl acrylate)-block-poly(N-isopropylacrylamide)

Anion Specificity Effects on the Interfacial Aggregation Behavior of Poly(lauryl acrylate)-block-poly(N-isopropylacrylamide)

Effects of Ionic Strength and Ion Specificity on the Interface Behavior of Poly(dimethylaminoethyl methacrylate)–Poly(lauryl methacrylate)

Aggregation behavior of the strong amphiphilic cationic diblock polyelectrolytes at the air/water interface

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